Obese people acting like they can’t control it is precisely why they’re obese. It’s vile to discriminate against someone for their height, race, sexual orientation, and other factors because they have no control or choice over those things. But if someone makes a bad choice that negatively affects their own health and others around them, it’s acceptable to tell that person it’s unsafe. Shaming them is ineffective, but just pretending being obese is normal and healthy isn’t ok either. These folks need help.
Don’t even start with me on thyroid disorders, those are a small fraction of people who are obese and even they do not defy basic laws of thermodynamics. Eat less than you burn, it’s basic math. You may not be able to control the disorder but you are in control of how you respond to it.